1. Field of the Invention
The disclosure relates to image formation apparatuses, and more particularly, to an image formation apparatus capable of adjusting image glossiness using a transparent toner in addition to cyan, magenta, yellow and black color toners.
2. Description of Related Art
Conventionally, there have been image formation apparatuses for printing using cyan (C), magenta (M), yellow (Y), and black (K) color toners (hereinafter referred to as CMYK color toners), and a transparent toner (for example, see Japanese Patent Application Laid-Open No. 2010-152209 (Pages 2 to 3, FIG. 1).
Some of the conventional image formation apparatuses that are capable of printing using CMYK color toners and a transparent toner create a histogram based on signal values of CMYK pixels contained in received image data, and select one of the following three printing modes on the basis of the histogram:
(1) if the highlight region including the non-printing portion is small, then printing is made with CMYK color toners at a low speed for glossiness;
(2) if the highlight region including the non-printing portion is large, then printing is made with CMYK color toners and a transparent toner at the normal speed; and
(3) if the region is large where a total amount of CMYK toners and a transparent toner superposed on the CMYK color toner image exceeds an upper limit total amount for the image formation apparatus, then printing is made twice (in two passes) with CMYK color toners at normal speed plus a transparent toner at normal speed.
However, for an image formation apparatus that adjusts image glossiness using a transparent toner in addition to color toners, it is difficult to obtain a glossy image by applying the transparent toner efficiently and effectively.